Nathan Bushyager

Determination of reactance loading for circularly polarized circular loop antennas with a uniform traveling-wave current distribution

A simple theory is presented to predict the lumped reactance loading for circularly polarized circular loop antennas with a uniform traveling-wave current distribution. The reactive load is located on a circular wire loop of one-wavelength circumference at a position of 45/spl deg/ away from the feed point. To achieve a uniform traveling-wave current distribution, the loading reactance and the input impedances of the loaded and unloaded loop antennas need to satisfy certain conditions. First, the input resistance and the input reactance of the unloaded loop antenna should have the same absolute value. Second, the input impedance of the loaded loop must be purely resistive and its value needs to be two times of the input resistance of the unloaded loop. Third, the loading reactance should be chosen to be two times in value and opposite in sense of the input reactance of the unloaded loop. These conditions can be approximately met when the circular loop is placed above a ground plane. The loading reactance is determined from the input impedance of the unloaded loop and is optimized for an optimal performance of circular polarization. It is found that the reactive load must be capacitive and its value depends on the height of the loop above the ground plane and the thickness of the wire. The characteristics of the circular polarization and the input impedance of the capacitance-loaded circular loop antennas are investigated. An experimental example is presented to verify the theoretical prediction.

Design and optimization of 3-D compact stripline and microstrip Bluetooth/WLAN balun architectures using the design of experiments technique

In this paper, various architectures of three-dimensional compact microwave balanced to unbalanced (balun) transformers for Bluetooth/WiFi antenna applications are successfully designed and optimized using the design of experiments (DOE) approach. Two different multilayer topologies, one microstrip and one stripline, are investigated on low temperature co-fired ceramic (LTCC) substrate. The design goals for both baluns are perfectly balanced outputs from 2 to 3 GHz and a resonant frequency of exactly 2.4 GHz. It is demonstrated, using only eight simulations, that perfectly balanced outputs are not possible under the given conditions in the case of the microstrip balun. Nevertheless, the stripline balun can be optimized due to its almost symmetrical structure, and both simulations and measurement results verify the conclusions. The DOE method is very simple to implement and gives a clear understanding of the system behavior at the beginning of the design process, reducing the amount of work required for achieving the design goals by orders of magnitude compared to the widely used trial-and-error approach. The matching and unique measurement issues regarding the calibration, placement of probes and the de-embedding of the microstrip to coplanar waveguide transitions are discussed in detail for the optimized stripline balun. This technique can be easily applied to the fast and efficient optimization of complicated radiation structures, such as reconfigurable or multilayer multiband antenna arrays.

RF-microwave multi-band design solutions for multilayer organic system on package integrated passives

We present multi-band design solutions for integrated passives using multilayer organic (MLO) process technology for RF and microwave System on Package (SOP) module development. The components developed in this technology include embedded high-Q compact inductors and filters designed in three frequency bands: S, C and Ku applicable for Bluetooth, MMDS, IEEE802.11a WLAN and satellite communications. Measured inductor Q-factor as high as 182 and Self-Resonant-Frequency (SRF) as high as 20 GHz, which represents the highest Q in its frequency range reported to date in a multilayer technology, have been demonstrated. A time domain electromagnetic modeling technique is also use to characterize the passive devices.

Analysis and design of MEMS and embedded components in silicon/LTCC packages using FDTD/MRTD for system-on-package applications (SOP)

The FDTD and MRTD full-wave numerical techniques are applied to the modeling and analysis of embedded components, such as MEMS, in silicon packages. Preliminary design rules are derived for minimized-crosstalk transmission lines, for a wideband compact transition, for a MEMS switch and that can be used in practical tuning applications and for a packaging adaptive antenna.

Modeling and optimization of RF reconfigurable tuners with computationally efficient time-domain techniques

Modern RF-MEMS device design is difficult due to the lack of tools capable of simulating highly integrated structures. This paper presents methods in which the FDTD technique can be used to model a reconfigurable RF-MEMS tuner. A new method of modeling a conductor intersecting a cell is presented. In addition, code parallelization and variable gridding are used to simulate the tuner. Results are presented showing the simulation and measurement results of the tuner.

Folded coplanar waveguide slot antenna on silicon substrates with a polyimide interface layer

A novel MM-wave coplanar waveguide (CPW) folded slot antenna is characterized on a low-resistivity Si substrate (1 /spl Omega/-cm) and a high resistivity Si substrate with a polyimide interface layer. The antenna resonates around 30 GHz with a return loss greater than 14.6 dB. Measured radiation patterns indicate the existence of a main lobe, but the radiation pattern is affected by a strong surface wave mode, which is greater in the high resistivity Si wafer.

A composite cell-multiresolution time-domain technique for the design of antenna systems including electromagnetic band gap and via-array structures

In this paper, the Haar-wavelet multiresolution time-domain (MRTD) scheme is modified in a way that enables the modeling of arbitrarily positioned metals within a cell, leading to the development of composite cells that are useful for the simulation of highly detailed structures. The technique is applied through the use of wavelet reconstruction and deconstruction matrices to explicitly set field values at perfect electrical conductor interfaces. Using this scheme, MRTD can be used to drastically reduce the number of cells needed to simulate complex antenna geometries including radio-frequency microelectromechanical systems, electronic bandgaps, and via arrays, while taking full advantage of the techniques inherent time- and space-adaptive gridding.

Optimization of 3D multilayer RF components using the design of experiments (DOE) technique

The successful use of the design of experiments (DOE) approach in an optimization feasibility study for two microwave balanced to unbalanced transformers (baluns) is presented. The medium of interest is the multi-layer low temperature cofired ceramic (LTCC) and two different topologies, one microstrip and one stripline, are investigated. The design goals are perfectly balanced outputs from 2-3 GHz and a resonant frequency of exactly 2.4 GHz. It is demonstrated, using only eight simulations, that perfectly balanced outputs are not possible under given conditions in the case of the microstrip balun. Nevertheless, the stripline balun can be optimized due to its almost symmetrical structure, and both simulations and measurement results verify the conclusions. The DOE method is very simple to implement and gives a clear understanding of the system behavior at the beginning of the design process, reducing the amount of work required for achieving the design goals by orders of magnitude compared to the widely used trial-and-error approach.

A novel adaptive approach to modeling MEMS tunable capacitors using MRTD and FDTD techniques

This paper introduces a novel full wave technique for modeling MEMS tunable capacitors that is based on the coupling of physical motion of the MEMS device with Maxwells equations through the modification of the MRTD/FDTD techniques. The difficulties of modeling MEMS devices are discussed, and ways to compensate for several of these are presented. The proposed approach is validated through comparison of simulation results to measurement for an interdigitated capacitor.

MRTD(Multi Resolution Time Domain) Method in Electromagnetics

Abstract This book presents a method that allows the use of multiresolution principles in a time domain electromagnetic modeling technique that is applicable to general structures. The multiresolution time-domain (MRTD) technique, as it is often called, is presented for general basis functions. Additional techniques that are presented here allow the modeling of complex structures using a subcell representation that permits the modeling discrete electromagnetic effects at individual equivalent grid points. This is accomplished by transforming the application of the effects at individual points in the grid into the wavelet domain. In this work, the MRTD technique is derived for a general wavelet basis using a relatively compact vector notation that both makes the technique easier to understand and illustrates the differences between MRTD basis functions. In addition, techniques such as the uniaxial perfectly matched layer (UPML) for arbitrary wavelet resolution and non-uniform gridding are presented. Using ...